Methods of making and using a chromatographic column comprising a flexible yarn as the solid support

ABSTRACT

A chromatographic column is manufactured by passing a guide member such as a needle or wire through a tubing of small diameter. The end of the guide member is secured to a continuous yarn, and the guide member is withdrawn to pull the yarn into the tubing. The yarm can be coated with a partitioning liquid. Various types of yarns, synthetic or natural, can be employed.

United States Patent Broerman I METHODS OF MAKING AND USING A CHROMATOGRAPI-IIC COLUMN COMPRISING A FLEXIBLE YARN AS THE SOLID SUPPORT Inventor:

[75] Arthur B. Broerman, Bartlesville,

Okla.

Assignee: Phillips Petroleum Company Filed: Feb. 12, 1968 Appl. No.: 704,702

US. Cl ..73/23.l, 55/197 Int. Cl. ..G01n 31/08, BOId 15/08 Field of Search ..73/23.l; 55/53, 67,

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 937,074 9/1963 Great Britain....'. ..73/23.l

UNITED STATES PATENTS 3.307.333 9/1967 Norem ..55/197 1 Apr. 17, 1973 OTHER PUBLICATIONS Journal of Chromatography-Vol. 26pp. 485-490 (1967). Sasaki et al-A Micro Gas Chromutograph Nature No. 472l-April 23, 1960-pp. 309-310 No.50A

Primary ExaminerRichard C. Queisser Assistant ExaminerC. E. Snee, lll Au0rney-Young & Quigg 57 ABSTRACT liquid. Various types of yarns, synthetic or natural,

can be employed.

2 Claims, 3 Drawing Figures METHODS OF MAKING AND USING A CHROMATOGRAPHIC COLUMN COMPRISING A FLEXIBLE YARN AS THE SOLID SUPPORT One of the most versatile analyzers which has been developed in recent years is the chromatographic analyzer. These instruments are capable of analyzing various complex mixtures in short periods of time by the use of appropriate separation columns. Probably the most common type of separation column is one which is filled with a solid packing material that can be coated with a liquid partitioning agent. Another type of column is generally referred to as a capillary column, which comprises a tubing of relatively small internal diameter, the interior surface of which is coated with a suitable separating material.

In order to make rapid analyses with samll samples, it is desirable to utilize chromatographic columns which are quite small in diameter. In constructing columns of this type, various problems are encountered. For example, it is extremely difficult to pack small diameter columns with solid materials. These materials can not readily be forced through the column, nor is there any assurance that a uniformly packed column will be obtained. This is true whether the materials are granular or in the form of fibers, such as described in US. Pat. No. 3,307,333. In accordance with this invention,-a chromatographic column is packed with a continuous porous yarn. The yarn is of such size and configuration as to substantially fill the interior of the tubing and provide a relatively large surface area. A continuous yarn V of this type can be inserted into tubes of extremely small diameter by the procedure of this invention. This is accomplished by extending a guide member such as a wire or needle through the tubing and attaching one end thereof to the yarn. The wire or needle is then withdrawn through the tubing to pull the yarn into the tubing. After being so positioned, a partitioning liquid can be passed through the tubing to coat the yarn. In another embodiment, a portion of the yarn can be dissolved by the use of suitable fluids to provide a packing material having greater surface area.

Accordingly, it is an object of this invention to provide a method of constructing improved chromatographic columns.

Another object is to provide chromatographic analyzers having improved columns of small cross-sectional area.

A further object is to provide an improved method of analyzing fluid samples by means of chromatography.

Other objects, advantages and features of the invention should become apparent from the following detailed description, taken in conjunction with the accompanying drawing in which:

FIG. 1 is a schematic representation of a chromatographic analyzer having a column constructed in accordance with this invention employed therein.

FIG. 2 is a view, shown partially in section, of a column constructed in accordance with this invention.

FIG. 3 illustrates the method of forming the chromatographic columns of this invention.

Referring now to the drawing in detail and to FIG. 1 in particular, there is shown a chromatographic analyzer which includes a column 10. Carrier fluid is introduced through a conduit 11 which communicates with the first inlet of a sample valve 12. The outlet of sample valve 12 is connected by a conduit 13 to the inlet of column 10. A conduit 14 introduces a sample of material to be analyzed into valve 12. The effluent from column 10 is directed through a conduit 15 to the first inlet of a detector 16. A conduit 17 extends between conduit 11 and the second inlet of detector 16 to pass a stream of carrier fluid to the reference side of the detector. Detector 16 can comprise thermal conductivity cells, flame detectors, or any other type of sensing elements known in the art.

The apparatus thus far described comprises a conventional chromatographic analyzer. In normal operation, carrier fluid initially flows through column 10 and through both channels of detector 16. Valve 12 is then actuated to introduce a predetermined volume of sample fluid into the carrier gas stream. The continued flow of carrier fluid results in the constituents of the sample appearing in the effluent from the column in sequence where they are detected by detector 16.

In accordance with the present invention, column 10 is packed with a continuous yarn which extends through an elongated tubing of small internal cross-sectional area. For example, this tubing generally has an internal diameter less than about 0.02 inch. As illustrated in FIG. 2, a continuous porous yarn 20 is positioned within such a tubing 21. The yarn normally extends throughout the length of the tubing, as illustrated.

After the yarn has been inserted, suitable tubing connectors, not shown, are secured to the ends of the tub ing for attachment to the inlet and outlet conduits. Tubing 21 can be formed of a metal, stainless steel for example, glass or other material, depending on the nature of the sample, carrier fluid and any partitioning fluid.

The yarn which is employed as the packing material in accordance with this invention is of such configuration as to provide a relatively large surface area. This yarn can be constructed of various types of materials, depending on the compositions of the sample and'carri- 'er fluids employed and the required temperature of operation. Examples of materials which can be employed for this purpose include various synthetic polymeric materials such as nylons, polyesters, polyolefins, polymers of halogenated hydrocarbons, polystyrene and the like. Other suitable materials from which the yarn can be constructed include carbon, graphite, quartz, glass, metals, amalgams, ceramics, ionic resins and cellulose. Various naturally occurring fibers, such as asbestos and kapok, can also be used. The yarn can be formed of a single fiber, or of a plurality of fibers which are twisted, braided, woven or grouped in any other manner. As used herein, the term yarn" is intended to include materials formed of a single fiber or a plurality of fibers so grouped or joined. It is often desirable that the yarn be bulked or texturized so as to substantially fill the interior of the tubing and provide a high surface area. Elastomeric yarns also serve this purpose. In one specific example of this invention, good separations have been obtained using a nylon braided fishing line with conventional liquid partitioning agents.

An important advantage in the use of yarn as the packing material resides in the ease of construction of the column. As previously mentioned, it is often difficult, if not impossible, to pack small diameter tubing with solid particles or individual fibers. The yarn of this invention, on the other hand, can readily be inserted within the tubing to provide uniform distribution. This can be accomplished, as illustrated in FIG. 3, by the use of a guide member which can be a wire or needle 23. Such a guide member is initially inserted through the tubing 21 until one end protrudes, which end can be provided with a slit to form a needle or bent over to form a hook 24. The end of the yarn 25 is secured to the end of the guide member and the guide member is then withdrawn from the tubing so as to pull the yarn I through the tubing. By this procedure, tubing of substantial length can readily be packed even though the tubing is in a coiled or other non-linear configuration. A flexible material such as piano wire can be employed to advantage for the guide member. The yarn illustrated in FIG. 3 is a braided nylon fishing line which has been found to be a good packing material in accordance with this invention. Most of the yarns employed in this invention possess sufficient resiliency to expand into contact with the inside surface of the tubing. For this reason, it is generally not necessary to provide any type of support at the ends of the column. This simplifies the column construction and avoids the danger of plugging at the ends of the column.

In order to increase the surface area of the yarn, various fluids can be passed through the column to dissolve or leach portions of the yarn. In some applications, particularly where the fluid is corrosive to the tubing, this leaching operation can take place before the yarn is inserted in the tubing. This can occur, for example, if hydrofluoric acid is being used to etch a glass yarn. After the yarn has been positioned within the tubing, a suitable partitioning liquid can then be passed through the tube to coat the yarn.. The various partitioning liquids known in the art can be used for this purpose.

While this invention has been described in conjuncl. The method of preparing apparatus for subsequentuse in the analysis of sample mixtures by the elution of constituents of such mixtures from a chromatographic column by passage of carrier fluid therethrough, whichmethod comprises passing a guide member through an elongated tubing of internal diameter, securing one end of said guide member to one end of a continuous, flexible yarn, withdrawing the guide member from the tubing to pull the yarn into the tubing, removing the guide member from the yarn to leave the yarn within the tubing so that the tubing and yarn form a chromatographic column, passing a fluid through the tubing to dissolve a portion of the yarn contained therein, thereby leaving yarn which has greater surface area than the. original yarn, coating the resulting yarn with a partitioning liquid, and securing tubing connectors to the ends of the tubing to permit attachment to inlet and outlet conduits for subsequent passage of carrier fluid and sample mixtures through the tubing.

2. A method of analysis which comprises passing a guide member through an elongated tubing of small intemal diameter, securing one end of said guide member to one end of a yarn, withdrawing the guide member from the tubing to pull the yarn into the tubing, passing a fluid through the tubing to dissolve a portion of the yarn contained therein so as to leave yarn which has greater surface area than the original yarn, coating the the sample, and detecting the constituents of the sample as they appear in the effluent from the tubing. 

1. The method of preparing apparatus for subsequent use in the analysis of sample mixtures by the elution of constituents of such mixtures from a chromatographic column by passage of carrier fluid therethrough, which method comprises passing a guide member through an elongated tubing of internal diameter, securing one end of said guide member to one end of a continuous, flexible yarn, withdrawing the guide member from the tubing to pull the yarn into the tubing, removing the guide member from the yarn to leave the yarn within the tubing so that the tubing and yarn form a chromatographic column, passing a fluid through the tubing to dissolve a portion of the yarn contained therein, thereby leaving yarn which has greater surface area than the original yarn, coating the resulting yarn with a partitioning liquid, and securing tubing connectors to the ends of the tubing to permit attachment to inlet and outlet conduits for subsequent passage of carrier fluid and sample mixtures through the tubing.
 2. A method of analysis which comprises passing a guide member through an elongated tubing of small internal diameter, securing one end of said guide member to one end of a yarn, withdrawing the guide member from the tubing to pull the yarn into the tubing, passing a fluid through the tubing to dissolve a portion of the yarn contained therein so as to leave yarn which has greater surface area than the original yarn, coating the resulting yarn with a partitioning liquid, introducing a sample of material to be analyzed into the tubing containing the resulting yarn, passing a carrier fluid through said tubing to elute therefrom constituents of the sample, and detecting the constituents of the sample as they appear in the effluent from the tubing. 